This invention relates generally to vehicles with canopies and, more specifically, to closing mechanisms for injection-molded canopies.
Modern aircraft canopies contain many parts. A transparent portion of the canopy may he replaced several times during the life of an aircraft due to scratches and general deterioration. Replacement of the transparent portion entails frame disassembly and reassembly. This is time-consuming, labor intensive, and costly.
Attempts have been made to produce frameless aircraft canopies in order to simplify replacement of the transparent portion, among other reasons. However, viable frameless canopy system must include a method for latching. As is known, the frame provides structural stiffness and strong, secure, attachment points for hinges and latches. Prior latching methods include a male hook or pin located on the aircraft structure or canopy frame and a female receiver on the canopy frame structure or aircraft structure respectively. Such discrete latching methods produce concentrated loads, which cause bearing stress in the transparency in the region of the latch.
Stress causes problems for transparencies. Glassy polymers craze at low stress levels. The effect of crazing on crack growth and localized failure is not well understood. Polymer transparencies yield at low stress levels and creep occurs after a fraction of service life. Cyclic, long-term loading, such as cockpit pressurization, induces creep and/or craze and reduces service life. Elevated temperatures, such as those experienced by high-speed aircraft, further increase the rate of creep and amplify the effect of crazing.
Therefore, there exists an unmet need to produce a latching system for an injection-molded canopy which avoids plastic creep and crazing due to concentrated loads yet securely holds the canopy in place.
The present invention provides a system and method for attaching an injection-molded canopy to a vehicle that avoids plastic creep and crazing due to concentrated loads while securely holding the canopy in place. The system includes a canopy rail attached to the vehicle and an injection-molded canopy that is molded to be securely received by the canopy rail. The canopy is at least one of a polycarbonate or acrylic frameless canopy. The system also includes a seal, a canopy position sensor for sensing position of the canopy, a sealing component, and a canopy handle for controlling position of the canopy. The sealing component inflates the seal with one of a liquid or gas when the canopy is sensed in the closed position
In one aspect of the invention, the vehicle is an aircraft and the system includes a ground sensor for sensing when the aircraft is on the ground. The sealing component deflates the seal if the canopy handle is in an open canopy position and the aircraft is sensed to be on the ground.
In another aspect of the invention, the canopy includes a channel for receiving the one or more seals.
In another aspect of the invention, the canopy is injection molded with protrusions, and the canopy rail includes flanges that mate with the protrusions when the canopy is placed in a closed and locked position within the canopy rail.